High Rate Determinations of Dimethyl Sulfide and Sulfur Dioxide during Rain In Cumulus over the Ocean (RICO)

二甲基硫化物（DMS）在海洋中产生并从海洋中释放出来，但在大气中衰变缓慢（主要通过氧化成二氧化硫）。它几乎不溶于云水，因此它为海洋云的边界层空气提供了很好的示踪剂。相比之下，二氧化硫很容易溶解在云水中，所以二氧化硫在云中的衰变可以提供云寿命的测量。在这项研究中，研究人员将测量DMS和二氧化硫，作为更广泛的“海洋上积云的雨”（RICO）实验的一部分，这是一个多研究者研究暖雨形成和信风积云特征的实验。他们将使用DMS来跟踪边界层空气进入云层并与上面没有DMS的空气混合，他们将使用二氧化硫浓度作为云寿命的指标。RICO的一个主要目标是了解暖雨的形成速度，因此云年龄的测量将对这一更广泛的研究做出有价值的贡献。DMS的测量结果还将表明，与来自上方的干燥空气混合后，云包的稀释程度。此外，研究人员还将研究云层内和云层附近的氧化过程，以及这些过程在新粒子形成或现有粒子生长中的作用。如果成功，这些测量技术将在未来的云研究中有广泛的应用。对未来能力的其他贡献包括在这一研究领域培训一名新的研究者，并为计划中的RICO研究生研讨会做出贡献，该研讨会将使研究生接触到这一研究领域的许多领导者。

Dimethyl sulfide (DMS) is produced in and released from the ocean but decays slowly in the atmosphere (primarily by oxidation to sulfur dioxide). It is also nearly insoluble in cloud water, so it provides a good tracer for boundary-layer air in oceanic clouds. In contrast, sulfur dioxide dissolves readily in cloud water so the decay of sulfur dioxide in clouds can provide a measure of cloud lifetime. In this study, the investigators will measure DMS and sulfur dioxide as part of the broader "Rain in Cumulus over the Ocean" (RICO) experiment, a multi-investigator study of warm-rain formation and the characteristics of trade-wind Cumuli. They will use DMS to track boundary-layer air as it moves into clouds and mixes with DMS-free air from above, and they will use sulfur dioxide concentration as an indicator of cloud lifetime. A primary objective of RICO is to understand the rate of warm-rain formation, so the measurement of cloud age will be a valuable contribution to that broader study. The DMS measurements will also indicate how much dilution of cloud parcels occurs by mixing with drier air from above. In addition, the investigators will examine the oxidation processes in and near clouds and the roles of such processes in the formation of new particles or the growth of existing particles. If successful, these measurement techniques can have broad applications in future studies of clouds. Other contributions to future capabilities include the training of a new investigator in this area of research and a contribution to the planned RICO graduate-student seminar that will expose graduate students to many of the leaders in this field of research.